Control of a Nano-carbon Film Electrode Surface for Highly Sensitive Detection of the Biomolecules

Introduction The electrochemical pretreatment (ECP) of graphite electrodes is well known to improve electrode activity. In contrast, ECP also induces an increase in the capacitive current and reduces the potential window of these electrodes owing to an increase in surface roughness and oxygen-containing groups. In contrast, the ECP of boron doped diamond (BDD) expands its potential window. However, the electron transfer rate at a BDD electrode becomes slower for several analytes after ECP. Improved electrode activity with a minimum increase in the background noise level and maintaining the wide potential window is ideal for detecting biomolecules with a low detection limit. We recently reported a newly developed carbon film consisting nanocrystallites with mixed sp and sp bonds formed by the electron cyclotron resonance (ECR) sputtering method. The film (ECR nanocarbon film) surface has controllable sp/sp ratios and is extremely flat.(1) This film electrode exhibited excellent electrochemical properties including a wide potential window, low capacitive current and low surface fouling, compared with the GC electrode. The electron transfer rates of several electroactive species at the ECR nanocarbon film electrode are higher than those at the BDD electrodes since the ECR nano-carbon film electrode has more sp bonds.(2,3) Investigation of the ECP of the ECR nano-carbon film electrode will be significant in extending its application to various biomolecules. In this work, we investigated the ECR nano-carbon film electrode with respect to morphological and characteristic changes caused by the ECP. We also investigated using a pretreated ECR nano-carbon film electrode to measure some biologically important analytes, including glutathione (oxidized form, GSSG) and serotonin.